1. Field of the Invention
The present invention relates generally to compact, lightweight vacuum insulated switchgears, and more particularly, to a vacuum insulated switchgear improved in operability and safety of a bus section panel.
2. Description of the Related Art
In general, vacuum insulated switchgears in power receiving/transforming equipment have busbars divided into a plurality of busbar sections to shorten a power interruption time associated with a busbar accident, and to improve the working efficiency of maintenance and inspection. One busbar section is constituted by a plurality of feeder panels arranged as panel arrays. A bus section panel that includes a circuit breaker to connect/disconnect busbars between two busbar sections is disposed between the panel array that constitutes one of the two busbar sections, and the panel array that constitutes the other busbar section.
Each feeder panel arranged in one panel array has, for example, vacuum switches of a double-break three-position type or the like, arranged in three horizontal lines on a single-phase basis as viewed from the front of the panel array. One connector for busbar connection is provided at an upper section of each vacuum switch, and longitudinal dimensions of these connectors from the front of the panel array vary from phase to phase. The busbars of each phase in the panel array can therefore be arranged next to one another in a lateral direction of the feeder panel.
In the bus section panel, on the other hand, vacuum switches of the double-break three-position type or the like are arranged in three horizontal lines on a single-phase basis as viewed from the front of the panel array, and two connectors for connection to different busbars are provided at both upper front and upper rear sections of each vacuum switch.
For example, busbars from the feeder panel located next to the immediate right of the above feeder panel are connected to an upper front connector of the double-break three-position vacuum switch. Likewise, busbars from the immediate left feeder panel are connected to an upper rear connector of the switch. These facts indicate that between the bus section panel and the feeder panel, since the busbars of each phase were unable to be connected in an adjacently arranged condition in the lateral direction of the panel, it has been likely for one busbar to interfere with the other busbars during the arrangement of each busbar.
In view of the problems described above, JP-2009-27767-A proposes a bus section panel in which busbar height differs for each phase.
The vacuum switches of the double-break three-position type (or the like) provided in the bus section panel establish and release busbar connection between different busbar sections. For inspection in the immediately right busbar section of the bus section panel (i.e., the panel array of a feeder panel), busbar connection to the immediately left busbar section (i.e., the panel array of another feeder panel) is released by opening a circuit breaker, for example. Additionally, an earthing switch corresponding to the immediately right busbar section inspected may be activated by earthing the busbars of the busbar section to ensure working safety.
In the bus section panel of the vacuum insulated switchgear discussed above, for example, when one of adjacent busbar sections is electrically charged, each vacuum switch is also charged at either of its front or rear side. When the bus section panel is visually seen from the front thereof, therefore, which of the adjacent busbar sections is charged cannot be readily discriminated. Charged internal panel constituent elements cannot be clearly discriminated either.
In addition, in the bus section panel, either or both of the adjacent busbar sections are usually charged and both very seldom enter a non-charged state. This makes it difficult to internally inspect the bus section panel itself under the non-charged state. For this reason, a vacuum insulated switchgear with a bus section panel that allows charged internal constituent elements of the panel to be checked for and a state of its busbar sections to be confirmed structurally, visually, and easily, is desired for safe inspection of the panel interior.
The present invention is based on the above, and an object of the invention is to provide a vacuum insulated switchgear including a bus section panel adapted to allow both an on/off state of a housing-contained circuit breaker and earthing switch, and a connection state of busbars in busbar sections to be confirmed structurally and visually from front.